New, Rapid Zika Test Has Been Working, UCSF Researcher Says

The Aedes aegypti mosquito is one of two species that can transmit the Zika virus.
(James Gathany, Centers for Disease Control )

Update March 8, 2016: As you can read in our original post below, we reported in February that Dr. Charles Chiu, a specialist in infectious disease at the University of California, San Francisco, has been testing a new genetic device that he hoped would diagnose the Zika virus in under six hours.

That would be significant because a faster diagnosis could help health officials better contain the spread of the virus, aid in identifying infection hot spots, and allow doctors to quickly inform pregnant women they've been exposed.

On Monday, Chiu gave us an update on the test's progress. Speaking with KQED's Lesley McClurg at the University of California, San Francisco symposium on preparing for Zika, Chiu said he's been using the test on samples from patients in South America and the Caribbean who were suspected of having the virus.

Chiu said the test, which uses a technique called nanopore sequencing, has been working well to not only identify Zika, but also co-infections, found in those who have, for example, both the Chikungunya and Zika viruses. Currently, there are separate tests for infectious agents like the malaria or chikungunya viruses.

Chiu's hope is the diagnostic test will be deployed in Barbados in the next month or two. A clinical microbiologist from Barbados will be coming to UCSF in the next two weeks to be trained on using the test, he said.

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Nearly 30 countries have reported outbreaks of the Zika virus, and the World Health Organization estimates that 3 to 4 million people may be infected by year's end. Transmitted by mosquito bites and -- in at least one case -- sexually, the virus has been associated with fetal microcephaly, a condition in which babies are born with abnormally small heads and brain damage.

"In a few months, we could use the device in the Zika-infected countries, although I’m hoping it's in a few weeks."
--Dr. Charles Chiu

No commercially available test for Zika virus exists. In the U.S., blood samples must be sent to the Centers for Disease Control, and it can take up to three weeks from the onset of infection for the test results to arrive.

A faster tool for diagnosis would help public health officials better contain the disease's spread, identify hot spots for infection, and allow doctors to quickly inform pregnant women if they've been exposed to the virus.

Dr. Charles Chiu, a specialist in infectious diseases at UC San Francisco, is testing a new genetic device that he hopes will diagnose Zika, and other mosquito-borne infections like dengue, in under six hours. If the technique proves successful, he hopes to send it to Brazil, ground zero for the virus, by the end of the month.

I interviewed Dr. Chiu on Wednesday.

This transcript has been edited for length and clarity.

Sheraz Sadiq: Can you describe this new technology that you're testing in your lab to see if it can quickly detect the Zika virus?

Dr. Charles Chiu: It’s a technique called nanopore sequencing. Oxford Nanopore, a biotech company from the UK, is the only company that provides it as a commercial product. It's a portable sequencer a bit larger than a USB stick, which can be powered by a USB connection on a laptop and can perform rapid sequencing.

Right now, we have one specific test for every infectious agent. So there’s now a test for Zika, for malaria, and for dengue. But this new technique allows us to use a single test to detect any bacteria, virus or parasite.

We're planning on testing Zika virus-positive and Zika virus-negative blood samples in my lab next week. If the tests are promising, we will then deploy the technology to affected countries for use in local clinics and hospitals.

With our tool, the turnaround time for test results can be under six hours.

Sadiq: Did you create this USB-sized sequencing device?

Chiu: No, but we are implementing and validating the technology for use with clinical specimens, and we are hoping to develop it into a clinical assay, so that you could also do the analysis in the cloud or on your laptop, to rapidly analyze hundreds of thousands of DNA sequences and give you an answer within minutes.

We recently published a study showing that we can identify Ebola or Chikungunya virus infection within 10 minutes.

The goal is to rapidly test and deploy this in other countries. In a few months, we could be using the device in the Zika-infected countries, although I’m hoping it's more like a few weeks.

Charles Chiu, M.D./Ph.D., is a professor at UCSF School of Medicine. (UCSF)

Sadiq: How long do you think it will take before a vaccine could be developed for the virus?

Chiu: I think typically the turnaround time for a vaccine is 10 years. Fortunately, we have a vaccine for one member of the mosquito-borne viruses - the yellow fever virus. And there’s discussion about how to modify this into a vaccine for Zika virus, and also test novel vaccine candidates for Zika.

With Ebola, there had been candidate vaccines available at various stages of development at the beginning of the outbreak, but with Zika there has been no development to date. So I think with Zika, it will probably be at least three to five years.

In the San Francisco Bay Area, for a full report on the Zika virus, watch Newsroom on Friday, Feb. 5, 8 p.m. on KQED Public Television 9, listen on Sundays at 6 p.m. on KQED Public Radio 88.5 FM. Repeat television broadcasts can be seen on KQED's digital channels.